The present invention relates to a variable flow divider for turbomachines, and more particularly for turbojet engines, consisting of several flaps arranged on a stationary casing section for pivotal movement about axes of rotation extending at right angles to the center axis of the engine.
Variable-cycle jet engines are characterized by the fact that their thrust and consumption characteristics can be varied within a certain range. This variation in engine characteristics is achieved by varying the mass flows within the engine, which is accomplished in part by adjustment of variable compressor and turbine guide vane cascades and in part also by admitting or interrupting streams of air, for example, compressor bleed air tapped when needed to cool the afterburner.
What all such engines have in common, however, is the selective division of the air mass flow downstream of the low-pressure compressor into a core stream and a bypass stream by means of a variable flow divider. For this purpose, the flow divider is preferably arranged in the area of the intermediate compressor casing for two-spool engines and in the area of the intermediate-pressure compressor for three-spool engines.
It is by no means an easy technical task, however, to design the flow divider plus its actuating mechanism and/or to arrange these components between the core stream duct and the bypass stream duct of the engine such that, if at all possible, the outer diameter of the engine will not be increased over that of an equivalent, fixed-cycle engine and that no additional hardware affecting the flows in the core and bypass ducts will be required.